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ber 5 to 8, and recommendations made to the association at the Jamestown meeting on October 9 to 12, in regard to any further changes or additions, before the revised methods are officially adopted.

Respectfully,

H. W. WILEY,
Chief, Bureau of Chemistry,

Secretary, Association Official Agricultural Chemists.

Twenty-five chemists sent criticisms of the revised methods. These criticisms were carefully considered by this committee and, in the main, were adopted, the majority being simply corrections of obvious errors in spelling, punctuation, printing, etc. Some chemists suggested material changes in official methods, which were not adopted, as the committee did not feel that it had the power to make such far-reaching modifications. When changes were suggested to make the statement of the method more clear, but not to change the method itself, these were adopted.

The committee would respectfully recommend that the methods as now published in Bulletin 107 and further corrected, as indicated above, be adopted as the official and provisional methods of the Association of Official Agricultural Chemists.

(Signed)

J. K. HAYWOOD, Chairman.

J. P. STREET,

A. L. WINTON,

F. P. VEITCH,

L. M. TOLMAN,

J. H. PETTIT,

F. W. WOLL (absent).

Upon a motion being made to adopt the report, a discussion ensued as to the extent of the authority of the committee to change the methods by dropping obsolete procedures and otherwise bringing the methods up to date and the several sections into harmony with each other, especially when changes in official methods were involved.

The original motion was amended by a motion to continue the committee with authority to make such further changes of this nature as might be deemed necessary, said changes to be approved by the execu tive committee and inserted in the final revision. This motion was passed, and the original motion as amended was then carried, adopting the report of the committee and making the revision official.

A vote of thanks was passed by the association in appreciation of the work of the committee on revision.

REPORT ON FOODS AND FEEDING STUFFS.

By J. K. HAYWOOD, Referee.

On account of a great pressure of official work it was impossible for the referee to send out samples for examination; however, some comparative work was done by two chemists (Messrs. Goodrich and Houghton) of the Miscellaneous Laboratory of the Bureau of Chemistry, working entirely independently of each other.

The method of determining methyl pentosans, originated by Ellett and Tollens, and reported, in a modified form, by the referee last year, was first considered. Varying quantities of gum tragacanth, which is known to contain some methyl pentosans, were subjected to analysis by the following method:

METHOD FOR DETERMINING PENTOSANS AND METHYL PENTOSANS.

Proceed as in the determination of pentosans by the provisional method (Bulletin 107, page 54) until the phloroglucid precipitate has been dried for four hours and weighed. Place the Gooch crucible containing this precipitate in a 100 ce beaker and pour into the Gooch 30 cc of 95 per cent alcohol heated to 60° C. Place the beaker for ten minutes in a water bath heated to 60° C. Remove the beaker and Gooch and draw off from the Gooch with a suction pump all alcohol remaining therein. Repeat this alternate extraction and sucking dry of the precipitate from three to five times, according to the color of the filtrate obtained. After the final extraction place the Gooch crucible in a water oven and dry four hours, making the final weighing in a closely stoppered glass weighing bottle, as described in the provisional method for pentosans.

The difference in weight between the furfural-phloroglucid plus methylfurfural-phloroglucid first obtained and the furfural-phloroglucid remaining after extraction with alcohol, minus 0.0037, represents the amount of methylfurfural-phloroglucid present, from which the original pentose (as rhamnose) can be calculated by the following formula:

Rhamnose (Ph) (165)—(Ph) (1.84)+0.010.

in which "Ph" equals the weight of methyl-furfural-phloroglucid; rhamnosan equals rhamnose multiplied by 0.8. A table giving these calculated figures will be found on page 19 of the article by Ellett and Tollens," in which attention is directed to an error in the calculation of 0.028 and 0.029 gram of the methylfurfural-phloroglucid to rhamnose.

To obtain the weight of pentosans, subtract the final corrected weight of methyl-furfural-phloroglucid from the weight of the mixture of methyl-furfuralphloroglucid and furfural-phloroglucid and calculate according to Kröber's table, or according to the formulas given in the present provisional methods for pentosans.

The following results were obtained by the two chemists engaged in the work:

TABLE 1.-Determination of pentosans and methyl-pentosans.

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TABLE I.-Determination of pentosans and methyl-pentosans—Continued.

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In interpreting these results, it must be borne in mind that gum tragacanth contains a very large amount of pentosans, larger, in fact, than almost any of the food or feed materials that the chemist will be called upon to examine; hence it was necessary to employ a small original weight of the gum, and this would result in small errors of weighing being very much magnified when the results were expressed on a percentage basis. Judging from Table I the method employed does not give as good results as was hoped. It will at once be seen from the work of both chemists that there is a tendency to get low results on methyl pentosans when the amount of gum tragacanth is increased. Expressing this in another way, there is a tendency for the amount of methyl pentosans to decrease as the weight of the furfural-phloroglucid + methyl-furfural-phloroglucid precipitate increases. This is probably due to the fact that the alcohol extraction is not so complete when a large precipitate is being handled. The results obtained by the same analyst on a definite weight of gum tragacanth do not vary from one another, in the large majority of cases, more than one would expect. The same can not be said of the results obtained by different analysts, which vary from each other more than is desirable even in such a conventional method. However, the averages obtained by the two analysts for methyl pentosans are close enough to warrant the referee for next year in sending out samples for further comparative work.

Even as the method stands it is worthy of adoption by the association as a roughly approximate method to be used by those who desire to make as complete an analysis as possible of vegetable materials. As the analysts become more familiar with the manipulation of the method, which is somewhat difficult and tedious, it is possible that their results will become more uniform. Better results will also be obtained upon the substances usually examined by feeding stuff methods than upon gum tragacanth, in which the amount of furfuralphloroglucid is so large that the extraction of the methyl-furfural-phloroglucid

is somewhat incomplete if a moderate quantity of the original gum is used. I would therefore recommend that the method be further studied next year, especial attention being given to obtaining a large amount of comparative work. Since calculating the percentages of methyl pentosans (as rhamnosan) from the formula given by Ellett and Tollens, an article by Mayer and Tollensa has appeared in which is given the formula for calculating the methyl-pentosans to fukose and also a table for calculating methyl-furfural-phloroglucid to fukose, fukosan, rhamnose, rhamnosan, and methyl pentosan (average of fukosan and rhamnosan).

I would, therefore, further recommend that this table be used in calculating the results of analysis, the average figure for methyl pentosans being taken when it is not known whether the mother product is fukosan or rhamnosan.

In accordance with instructions from the association, a study was also made of the time required to dry the crude fat obtained in the ether extract determination on several different feeding stuffs. The dryings were made at the temperature of boiling water and the following feeding stuffs were employed: Wheat germ meal, ground corn, cotton-seed meal, and flaxseed. To be certain that all fat was extracted from the samples, the time of extraction with ether was increased from sixteen to about twenty-four hours. The following results were obtained by the two chemists engaged in the work:

TABLE II.-Determination of time required to dry the crude fat obtained in ether extracts from different feeding stuffs.

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It is at once evident from these results that no definite period for drying the crude fat can be specified in the method for determining this substance in cattle food materials. The time necessary to obtain a minimum weight evidently varies with the individual performing the work, with the amount of substance taken, with the character of the fat extracted, with the amount of fat in the substance, and possibly with other factors. A second point brought out is one that would be expected, i. e., that there is a marked tendency for the fat to reach a minimum weight and then slowly to gain by oxidation of the fat. This is, of course, particularly well marked in the case of linseed, which contains an oil that has a high oxygen-absorbing power.

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A third point made evident by this investigation is, that in every case at least a one-hour period of drying was necessary to reach a minimum weight, while in some cases this period was extended to two and one-half hours. large majority of cases a one and one-half hour period of drying the crude fat was sufficient to obtain either a minimum or results so close to the minimum that the difference was negligible. On the whole, then, while a definite time of drying the fat can not be specified, it may be of some service to the inexperienced to state that the time is usually between one and one-half hours.

I would recommend, therefore, that the last sentence under Crude Fat, or Ether Extract, Direct Method, page 39, Bulletin 107 (Methods of Analysis), which now reads, "Dry the extract at the temperature of boiling water until it ceases to lose weight," be changed to read, “Dry the extract at the temperature of boiling water for one-half hour, remove from the oven to a desiccator, let it cool, and weigh; continue this every alternate one-half hour, drying and weighing until a minimum weight of the fat is obtained. For most substances a period of one to one and one-half hours is required to obtain a minimum weight."

REPORT ON SPECIAL ANALYTICAL METHODS OF SUGAR ANALYSIS. By C. A. BROWNE, Referee.

The work of the referee on special methods of sugar analysis for the present year has covered the investigation of a number of carbohydrate products, but the present report will be limited to a discussion of only three of these: First, the analysis or assay of commercial dextrins; second, a comparison of methods for the estimation of glucose in honey, and third, a study of methods for detecting artificial invert sugar in honey.

ASSAY OF COMMERCIAL DEXTRINS.

During the past year the Bureau of Chemistry has had occasion to analyze a number of dextrins for the work of the Bureau of Engraving and Printing. As a basis for methods an extensive article by Friedrich Lippmann a upon the “Examination and analysis of commercial dextrins" was used. An abstracted translation of this article has been prepared by the referee, and copies so far as available can be furnished to members of the association.

The methods described in this abstract for moisture, ash, insoluble organie matter, and reducing sugars, were followed, and the difference between these and 100 per cent taken as dextrin, as advocated by Lippmann. It should be noted, however, that this difference includes other cold-water soluble organic materials besides dextrin, such as acids, proteid bodies, and various decomposition products of a carbohydrate nature formed during the process of dextrin

a Zts. Spiritus-Ind., 25: 304, 307, 316, 317.

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